.ok {
    background-image: url(../images/default/tree/drop-yes.gif) !important;
}
.cancel {
    background-image: url(../images/cancel.png) !important;
}
.search {
    background-image: url(../images/search.png) !important;
}
.edit_add {
    background-image: url(../images/edit_add.png) !important;
}